Manufacture of absolute alcohol



May 3l, 1932. E. RICARD ET AL MANUFACTURE oI1 ABSOLUTE ALCOHOL Original Filed April 16,' l1928 .v /NVENTRS A ToR/VEY Patented May 31, 1932 UNITED STATES PATENT OFFICE ELOI RICARD, PAUL SAVARIT, AND HENRI MARTIN GUINOT, OF MELLE, FRANCE, ASSIGNORS TO U. S. INDUSTRIAL ALCOHOL CO., OF N EW YORK, N. Y., A CORPORATION F WEST VIRGINIA 1 y MANUFACTURE OF ABSOLUTE ALCOHOL Original application led March 28, 1929, Serial No. 350,809, and in France .April 3, 1928. Divided and this application filed October 24, 1930. Serial No. 490,840.

In our prior application Serial No. 27 0,337, filed April 16, 1928, we have disclosed an improvement in the manufacture of absolute alcohol from fermented mashes containing aqueous alcohol, having for its object an important reduction in the amount of steam required for heating, in order'to reduce the cost of manufacture of the alcohol. In that application the heat of the alcoholic vapors issuing from the column used for distilling the mashes at a very high degree was utilized for heating the dehydrating column, either partially or entirely.

This was accomplished by conducting the alcoholic vapors leaving the top of the distilling column to a coil in the dehydrating column, and causing condensation to take place in this coil, so that the contents of the deliydrating column were heated indirectly by the sensible and latent heat relinquished by the vapors. The resultin condensate was returned to the mash distil ing column and the uncondensed vapors were likewise condensed and returned to that column.

The temperature of the vapors passing from the distilling column when operating at atmospheric pressure is such that they can be employed in this way to heat about three- I quarters of the dehydrating column, but the basal portion of this column must be maintained at a higher temperatureand conse.

quently, in one form of execution of the invention of our earlier application, a steam coilwas rovided for heating the lower part of the de ydrating column.

We also disclosed, however, that the entire heating of the dehydrating column (leaving out of account the heat contained in the raw alcohol to be dehydrated) could be supplied by the alcoholic vapors in the manner described, by maintaining the distilling column under a pressure suiiicient to raise the temperature of the alcoholic vapors to the requisite degree.

'Wehave discovered that we can realize a modification of the rocess if, instead of maintaining the distilling column under pressure we maintain all or part of the dehydration apparatus under a pressure less than atmospheric pressure, and preferably at a pressure sufficiently reduced so that the dehydrating column will operate at a tempera ture several degrees below1 78 C. at the base. In this way the heat of the vapors circulated from and back to the distilling column can be made to suiiice for heating the entirety of the dehydrating column and secondary column, or if the pressure in the dehydrating apparatus is lowered but a less extent, the amount of additional steam heating that may be required will be correspondingly' reduced.

The accompanying drawing illustrates in diagram an apparatus for carrying out the present invention.

The distilling column 1 is heated by steam at 2. The fermented mash, for example a 7% (Gay Lussac) mash, to be distilled is supplied continuously through the pipe 3 and as in ouiformer application becomes heated to 90 C. in a heat-exchange device '4, where it is heated by the distillers wash which is discharged from the bott-om of the distilling column at 6 and after being cooled in the heat-exchanger is conducted away through a pipe 7. The heated mash proceeds through a pipe 5 to the column l.

Distillation in this column is conducted so as to produce high grade raw alcohol, preferably E350-95.5 Gray Lussac, and this alcohol passes through the pipe 16 to the second distilling column 10, which is the dehydrating column. Here the alcohol is subjected to azeotropic distillation in the presence of a suitable water entrainer, such as benzol for example, with which this column is charged. The dehydrated or absolute alcohol is drawn oif at the base of this column through a pipe 25 to a cooler 50 having a vented outlet pipe 51.

The vapors issuing from the top of the dehydrating column pass through the pipe 52 to a'condenser 18, from which the condensate flows through a. pipe 52 toa decanting apparatus19, Where it separates into two layers. The layer rich in entrainer is continually returned through a pipe 20 to the dehydrat ing column, while the liquid composing the l,distilling column 10.

The alcoholic vapors issuing from the top of the column 1 through the pipe 8 areutilized for heating the dehydrating column 10 and also preferably the secondary or small column 22 in the'manner previously referred to, and in accordance with the resent invention the eli'ect of these vapors 1n heating the dehydration apparatus is increased by ,maintaining the dehydratingcolumn 10 or both this column and the secondary column 22-under a slight vacuum. According to the degree ofthe vacuum, the vapors will be made eifective to heat the columns of the dehydrat-l ing apparatus more nearly to the bottom than would otherwise be the case, while by choosing a degree'of minus pressure whic enables the dehydrating column to operate at a temperature several degrees below 78` C. at the base it becomes possible to heat the entirety of the dehydrating apparatus, without any additional steam heat, and without operating the distilling column under pressure, or without compressing the vapors after they leavelthis column, as disclosed in our application Serial No. 350,809, filed March 28, 1929, of which ythis application is a division. However, the invention is not necessarily limited to the heating of the columns 1() and 22 in their entirety in this way, or t0 operation of the distilling column 1 at atmospheric pressure.l

In order tomaintain the dehydrating apparatus-under sub-atmospheric pressure, a partial vacuum chamber is provided, this chamber being connected by a line 71 with an exhausting pum not shown. This chamber is connected with the dehydrating system at suitable points. Thus, it is shown connected by pipes 72, 73 and 74 with vents in the conduits 53, 21 and 51.

The pipe 8 has branches 18 andl 34 which conduct the alcoholic vapors to condensing andv heating coils 9 and 33 in the base` of columns l0 and 22, respectively, whereby the contents of' these columns are heated by sensible and latent heat surrendered by the vapors.

The outlet of coil 9 is connected with a separator 56 from which there extend a vapor pipe 11 and a liquid-conducting pipe 14. Uncondensed vapors rise through the pipe 11 toa condenser 12, from which the condensate passes to a separator 57 having a vent 58 to the'atmo'sphere and is returned through a pipe 13 to the distilling column 1.

The liquid condensed in the coil 9 is elevated by any suitable pump or lift 15 in the pipe 14 and is also returned to the column 1, all of the alcoholic vapors used for heating the dehydrating column being condensed and returned to the distilling column where separator 59, "from which thel liquid resulting `from condensation in the coil ,flows v.

through a pipe 36 to the pipe 14, and is returne by the lift device 15 to the distilling column 1. Vapors'which pass through the coil 33 without being condensed rise through a pipe-35 and thence tothe condenser 12,

Afrom which the condensate is returned to the column. Thus, as in the case of the vapors used for the heating of column 10, all the vapors utilized for the heating of column 22 are circulated in a closed cycle, are condensed and returned to the column where the mash is being distilled.

' We claim:

1: A continuous process for the manufacture of absolute alcohol from dilute aqueous alcohol, which comprises distilling the dilute aqueous alcohol in one apparatus, and dehydrating the alcohol'thus obtained in another apparatus, and heating the dehydration apparatus b circulating alcoholic vapors from the first distilling apparatus so that they condense in indirect heat-exchange relation with the contents of the dehydration apparatus' and return tothe first distilling apparatus," which rocess is further'characterized in that the'de ydration apparatus is maintained at least in part under sub-atmospheric pressure in order to increase the effect ofthe alcoholic lyapors for heating the dehydration appara- 2. A continuous process for the manufacture of absolute alcohol from dilute aqueous alcohol, which comprises distilling the dilute aqueous alcohol in one apparatus, and dehydrating the alcohol thus obtained inanother apparatus andheating the dehydration apparatus by circulating alcoholic 'vapors from the first distilling apparatus so that they condense in indirect heat-exchange. relation with the contents of the dehydration apparatus and return to the rst distilling apparatus, which process is further characterized in that the dehydration apparatus is maintained at least in part at a pressure sufficiently below atmospheric pressure so that the alcoholic vapors suliice for heatingjsuch apparatus without additional heating. 

